Wet Conditions Research Articles

A global Data Assimilation of Moisture Patterns from 21 000–0 BP (DAMP-21ka) using lake level proxy records

Abstract. Global hydroclimate significantly differed from modern climate during the mid-Holocene (6 ka) and Last Glacial Maximum (21 ka). Consequently, both periods have been described as either a partial or reverse analogue for current climate change. To reconstruct past hydroclimate, an offline paleoclimate data assimilation methodology is applied to a dataset of 216 lake status records which provide relative estimates of water level change. The proxy observations are integrated with the climate dynamics of two transient simulations (TraCE-21ka and HadCM3) using a multivariate proxy system model (PSM) which estimates relative lake status from available climate simulation variables. The resulting DAMP-21ka (Data Assimilation of Moisture Patterns 21 000–0 BP) reanalysis reconstructs annual lake status and precipitation values at 500-year resolution and represents the first application of the methodology to global hydroclimate on timescales spanning the Holocene and longer. Validation using Pearson's correlation coefficients indicates that the reconstruction (0.24) is more skillful, on average, than model simulations (0.09), particularly in portions of North America and east Africa, where data density is high and proxy–model disagreement is prominent during the Holocene. Results of the PSM and assimilation are used to evaluate climatic controls on lake status, spatiotemporal patterns of moisture variability, and proxy–model disagreement. During the mid-Holocene, wetter conditions are reconstructed for northern and eastern Africa, Asia, and southern Australia, but in contrast to the model prior, negative anomalies are observed in North America, resulting in drier-than-modern conditions throughout the Northern Hemisphere midlatitudes. Proxy–model disagreement in western North America may reflect a bias in model simulations to stronger sea level pressure gradients in the North Pacific during the mid-Holocene. The data assimilation framework is able to reconcile these differences by integrating the constraints of proxy observations with the dynamics of the model prior to produce a more robust estimation of hydroclimate variability during the past 21 000 years.

Are conductivity sensors useless for irrigators? Exploring measurement consistency around soil moisture thresholds relevant to different applications

AbstractThe cheap conductivity‐based sensors favoured by farmers for soil moisture monitoring remain largely ignored by researchers because of their low accuracy, which results in high uncertainty regarding their utility for irrigators. In this work, conductivity measurements were compared with dielectric permittivity measurements in moisture ranges relevant to different applications. The results showed that the permittivity measurements captured moisture variability well (R2 > 0.8) throughout the full range tested (0%–35%), which is consistent with the literature. Conductivity measurements consistently distinguished dry from wet conditions (p < 0.0001) and reflected moisture variability in lower ranges (R2 > 0.5) but not in higher ranges (>20%). This is problematic because important monitoring thresholds such as field capacity and saturation are in the upper moisture ranges. Conductivity measurements were found to lack any meaningful utility in most applications except those relevant to distinguishing dry from wet conditions and indicating lower‐range moisture patterns, such as monitoring in arid environments. This gives some merit to conductivity sensors considering their very low cost if corrosion is minimised. The described evaluation approach is suggested as an example for developers, labs and extension services to better communicate potential sensor utilities and restrictions to practitioners to improve their accessibility to decision support technologies.

The East Asian monsoon variability in the Nihewan Basin, northern China, during the Early Pleistocene: A grain size end-member modelling analysis

The Pleistocene sediments of the Nihewan Basin in northern China preserve a detailed terrestrial sediment archive for reconstructing the palaeoenvironment and palaeoclimate changes during early times of hominin occupation in E Asia, following the earliest locations outside of Africa. In this study, we investigate the composite 86.2-m long NH-T section of Dachangliang which was formed with an astronomically tuned age between ca. 1.66 and 0.78 Ma. Parameterized grain size end-member modelling analysis is applied for the first time in the Nihewan Basin to unravel the characteristics of sediment sources, transportation dynamics, and climatic signals in the region. The grain-size distributions of the NH-T sediment samples are attributed to a mixture of four distinct end members (EMs 1-4). EM 1 represents a global atmospheric fine silt component (mode at 7.9 μm) which probably resulted from high-altitude westerly transport from distal sources. EM 2, a medium silt component (mode at 27.6 μm) was probably transported by the low-level westerly winds during the spring from a relatively proximal source in comparison to EM 1. EM 3, a coarse silt component (mode at 59.9 μm), represents short distance suspended materials that were blown out by N or NW winds of the East Asian winter monsoon (EAWM). EM 4 is a fine sand component (mode at 221.1 μm), probably representing fluvial deposits carried by overland flow. Therefore, the temporal fluctuations in the abundances of EMs 1-3 are used to infer the history of the East Asian summer monsoon (EASM) (EM 1), of dust-storm outbreaks during springtime (EM 2), and of the EAWM (EM 3). The NH-T climate record shows an overall increase in EM 3 peaks, accompanied by a decrease in EM 1 minima from ca. 1.45 to 0.82 Ma, indicating a long-term aridification and cooling trend in the Nihewan Basin. At ca. 1.25 Ma, the EM patterns transition from short-frequency to longer fluctuations, apparently coinciding with the onset of the Mid-Pleistocene transition (MPT). Periods of stronger EASM with more frequently warm and wet conditions probably occurred in the basin between ca. 1.66-1.62, 1.52-1.25 and after 0.82 Ma. Intensified EAWM conditions probably prevailed in the basin during the intervening periods from ca. 1.62-1.52 and the MPT 1.25-0.82 Ma. The inferred warmer and wetter conditions likely supported hominin activities in the Nihewan Basin, in contrast to mostly colder and drier conditions. Nevertheless, the higher number of discovered Palaeolithic sites and recorded lithic artifacts from the first half of the MPT apparently reflects the successful adaptability of hominins to the prevailing cold climate. The relatively consistent patterns observed between the variations of a median grain-size stack of the Chinese Loess Plateau (CLP MD) and EM 3, and of the magnetic susceptibility stack of the CLP (CLP MS) and EM 1, indicate the climatic sensitivity of these EMs in response to the long-term glacial/interglacial oscillations previously inferred from the CLP. However, significant differences in the CLP MD and CLP MS on the one hand side and in the trends of the EMs 3 and 1 on the other suggest that regional climate conditions varied between the CLP and the Nihewan Basin. Further research is required to explore such regional climate differences and their possibly underlying factors in the Early Pleistocene.

Ecological Functions of Autumn Olives for Improving Vegetation Species Diversity and Habitat Conditions Supporting Their Growth: A Study of Tedorigawa River, Japan

ABSTRACTThus far, no studies have quantitatively investigated the ecological functions of wood communities for increasing vegetation species diversity and promoting supportive habitat conditions for their growth. To fill this gap, this study investigates the ecological function of the autumn olive (Elaeagnus umbellata var. umbellata) community, a typical native wood community of Japan. We selected the Tedorigawa River, a representative rapid river of Japan, as a case‐study subject and conducted field surveys to investigate the relationships between the autumn olive, black locust, and oriental wormwood‐kawarahako communities (among six total vegetation communities) and their respective species compositions. Hydraulic simulations helped investigate significant differences in the cover ratio of native species that grow in rivers and alien species and, differences in the physical and environmental characteristics among the three typical vegetation communities in the river channel (native grass community, native wood community, and alien wood community). The results showed that autumn olives support the growth of native species that prefer wet conditions and control alien species' growth. This ecological function is supported by the characteristic hierarchical structure of autumn olives, including low‐density trunks and leaves and low height, which create bright light conditions in the community. The autumn olive community was also found to obstruct flood flow, which enhances the deposition of fine sediments and nutrients. These characteristics enhance wet conditions to support the growth of native species that prefer these conditions.

Identifying the Mechanism of Interaction Between Soil Moisture State and Summertime MCS Initiations in Weakly Forced Synoptic Environments Using Convective-Permitting Simulations.

This work aims to identify a mechanism of interaction between soil moisture (SM) state and the incidence of weakly forced synoptic scale MCS events during boreal summer by performing a sensitivity study using the Weather Research and Forecasting (WRF) model over the US Great Plains. A uniformly dry SM patch at a 5°×5° scale is centered at the point of a documented MCS initiation to observe spatiotemporal changes of the simulated MCS events, totaling 97 cases between 2004 and 2017. A storm-centered composite analysis of SM at the location of simulated MCS events depicted SM heterogeneity [O(100) km] structured as significantly drier soils to the southwest (SW) transitioning to wetter soils northeast (NE) of the mean simulated initiation. Further analyses showed that this SM configuration influenced near-surface fluxes, which created a gradient of 2m-temperature and 2m-humidity, also aligned SW-to-NE, which affected the growth of the planetary boundary layer to trigger MCS initiations earlier in time (∼1-2hr on average) compared to Control simulations. The implementation of the dry SM perturbation introduced drier-to-wetter SM gradients along the edges of the perturbed area, and MCS initiations were subsequently preferred on the drier side of those transition zones, with the most common orientation of simulated MCS events embedded within southwesterly flow. These results emphasize the importance of the low-level wind field alignment to organized SM gradients, which suggests that SM heterogeneity can drive MCS initiation related to near-surface atmospheric variable fluctuations as the main mechanism of interaction in weakly forced synoptic environments.

A fully remote sensing-based implementation of the two-source energy balance model: an application over Mediterranean crops

Applications of the two-source energy balance (TSEB) scheme require either in-situ meteorological data to characterize the upper boundary conditions or the implementation of complex multi-scale approaches (ALEXI/DisALEXI). Over remote areas, detailed meteorological forcing (i.e., air temperature and wind speed) are often missing, limiting the quality of the simulated fluxes. To compute surface energy fluxes, the use of wet and dry boundary conditions, commonly referred to as hot and cold pixels, is a widely adopted strategy in thermal-based, single-source surface energy balance models for defining the relationship between satellite land-surface temperature (LST) and the surface-atmosphere temperature gradient. This contextual scaling approach reduces model sensitivity to biases in LST retrievals, but it has been previously tested within the TSEB modelling framework only in limited capacity. An automatic procedure for retrieving the two boundary temperatures is here proposed, removing the need for external meteorological data and leading to temperature values that are unbiased compared to ideal estimations (from in-situ observations) and characterized by deviations on the order of 1.5 and 4.5 °C for cold and hot conditions, respectively. Despite the lower accuracy in the hot pixel temperature, this does not seem to significantly affect the overall capability of the model to reproduce observed fluxes, with errors in instantaneous sensible and latent heat fluxes in the order of 60 W m−2 (slightly above 1 mm d−1 on daily evapotranspiration) over a set of 16 sites in the US and Italy, characterized by typical Mediterranean crops. The proposed TSEB implementation is fully remote sensing based, meaning satellite-consistent retrievals of air temperature and wind speed are obtained directly from information available within the satellite scene itself. This approach represents a suitable alternative to accurately model evapotranspiration and other surface energy fluxes in the absence of reliable meteorological data.

A review of paleofloods in the middle-lower reaches of the Yangtze River during the Holocene: Processes, causes and effects

The understanding of the flooding processes in the entire basin of the middle-lower reaches of the Yangtze River (MLRYR) during the Holocene remains elusive. This is primarily attributed to the constraints posed by site-scale data characterized by limited spatiotemporal resolutions, compounded by conflicting results of the reconstructed Holocene paleoflood records in some of the previous studies. In this study, by synthesizing 114 paleoflood data with robust evidence of flood occurrence (including timing and location of flood occurrence), we comprehensively reconstructed the first continuous Holocene paleoflood record that cover the entire basin of the MLRYR. The results show that at the onset of the Holocene, flood frequency peaked notably in the middle reaches of the Yangtze River (MRYR), with no corresponding peak observed in the lower reaches of the Yangtze River (LRYR). However, in both the MRYR and LRYR, a significant flood frequency peak emerged around 8.0 ± 0.5 ka BP, and scarce flood occurrences appeared approximately 7.5–5.0 ka BP. This scarcity shifted abruptly to a surge in flood frequency from 5.0–4.0 ka BP. Following this, the MRYR witnessed three successive peaks in flood frequency, occurring at approximately 3.0 ka BP, 1.8 ka BP, and 1.0 ka BP, respectively. In contrast, flood events in the LRYR were infrequent during the 3.0–2.0 ka BP period, followed by a surge in frequency from 2.0 ka BP onwards. We further explored the driving mechanisms of paleofloods in the MLRYR and found that floods were more likely to occur during periods of weakened EASM, characterized by wet and unstable climate conditions in the MLRYR. Marine erosion may be also a key factor in the lack of geological evidence for palaeofloods during the early Holocene. Additionally, variations in the ISM and human activities during the late Holocene have significantly influenced the occurrence of floods in the MLRYR. By comparing the paleoflood frequency with the spatial distribution and number of archaeological sites in the MLRYR, respectively, we propose that the period of flood scarcity during the middle Holocene may have facilitated the development of rice agriculture and the prosperity of ancient settlements. In contrast, during flood-prone period, ancient societies adapted and coped with floods by migrating to higher terrain during the early Holocene and implementing simple hydraulic engineering techniques during the late Holocene.

Preparation and performance study of three-dimensional interconnected structured electrodes with lamellar connections

In this study, we developed an innovative strategy to fabricate perovskite oxide powder with 12.356 m2/g of specific surface area. Polyacrylamide hydrogel was used as a template to prepare Sm0.5Sr0.5CoO3-δ (SSC) powders with lamellar structure. The three-dimensional interconnected structured SSC electrodes with lamellar connections were fabricate using screen printing method. As a result, the oxygen vacancy concentration of the SSC powder obtained by the polyacrylamide template method was 0.625 and 0.642 at 650 °C and 700 °C respectively. At 650°C, the polarization resistance value was 0.11 Ω cm2 for the novel SSC-PAM-V cathode. Compared with the SSC-SG cathode, the polarization resistance and activation energy of SSC-PAM-V were reduced by 50 % and 6.9 %, respectively. Furthermore, in a single cell with SSC-PAM-V electrodes, we achieved a maximum power density of 935 and 1243 mW cm−2 at 650 °C and 700 °C under wet H2 conditions, demonstrating good electrochemical output performance. The layered porous electrode was not only suitable for the diffusion of oxygen, but also for increasing the reactive active sites. The proposed powder prepared with polyacrylamide hydrogel as template, was not only suitable for the optimization of perovskite oxide, but also for the application in other types of catalysis, providing the potential for improving the electro-catalytic activity of perovskite electrodes.

Quantitative Impact of Monthly Precipitation on Urban Vegetation, Surface Water and Potential Evapotranspiration in Baghdad Under Wet and Dry Conditions

Precipitation is a fundamental variable that is widely used in the organization of water resources and has a great influence on hydrological processes and ecological assessment. This study investigated the quantitative effect of monthly precipitation on surface water area (denoted by the Modified Normalized Difference Water Index, MNDWI), vegetation area (denoted by Normalized Difference Vegetation Index, NDVI), and potential evapotranspiration (PET) during two years (2018 and 2021) in the city of Baghdad, Iraq. Using the Thornthwaite aridity index, the annual aridity was first assessed to quantify the climate category of these years. The result shows that they were semi-arid and very arid, respectively. The empirical relationships between precipitation and areas of MNDWI and NDVI, and between rainfall and PET, were also examined. Due to less precipitation in 2021, no relationship was found in arid climates, while in 2018 for semi-arid climates, precipitation had a positive non-linear correlation with MNDWI and NDVI areas and a negative correlation with PET.

The role of diabatic heating/cooling in outer rainbands in the secondary eyewall formation and evolution in a numerically simulated tropical cyclone

In this study, the role of diabatic heating/cooling in outer rainbands (ORBs) in the formation and evolution of the secondary eyewall of a numerically simulated tropical cyclone (TC) is investigated. This is done through a series of sensitivity experiments under idealized conditions using a high-resolution cloud-resolving atmospheric model. The results show that artificially increasing diabatic heating in rainbands enhances convective activities in ORBs and leads to an earlier secondary eyewall formation (SEF), and later the faster weakening and earlier dissipation of the primary eyewall. Reducing diabatic heating in ORBs weakens the rainbands and delays the SEF but prolongs the duration of the double eyewall structure if the SEF occurs. Reducing diabatic cooling in ORBs enhances convective activity in rainbands but has little effect on convection in the primary eyewall prior to the SEF. However, it results in a widened eyewall structure and a stronger TC after the eyewall replacement. Increasing diabatic cooling in ORBs largely suppresses convection in rainbands and prohibits the SEF. These results demonstrate that diabatic heating/cooling in ORBs plays important roles in the SEF and evolution. Since diabatic heating/cooling in rainbands is sensitive to the near-core environmental relative humidity, our results demonstrate the critical importance of large-scale environmental moist condition to the formation and evolution of secondary eyewall in TCs. In addition, it is also found that when the area-averaged diabatic heating rate in ORBs becomes similar in magnitude to that in the primary eyewall, the secondary eyewall forms. Plain language summaryPrevious studies have demonstrated the importance of diabatic heating/cooling in outer rainbands to the structure and intensity changes of tropical cyclones (TCs) with a single eyewall. It is unclear whether and how diabatic heating/cooling in outer rainbands may affect the formation and evolution of the secondary eyewall in TCs. These issues have been addressed based on a series of sensitivity experiments under idealized conditions using a high-resolution atmospheric model. Results show that diabatic heating in outer rainbands is favorable for the secondary eyewall formation (SEF). Increasing diabatic heating in outer eyewall can lead to faster weakening and thus earlier dissipation of the primary eyewall. Diabatic cooling in outer rainbands suppresses convection in outer rainbands and prohibits the SEF. Since diabatic heating/cooling in outer rainbands is sensitive to the near-core environmental relative humidity, our results demonstrate the importance of the large-scale environmental moist condition to the SEF of TCs. We also found that when the area-averaged diabatic heating rate in outer rainbands becomes similar in magnitude to that in the primary eyewall, the secondary eyewall would form, which can be considered as a measure of the SEF in TCs. Key points1.Increasing diabatic heating in outer rainbands leads to earlier SEF, and faster weakening and earlier dissipation of the primary eyewall.2.Increasing diabatic cooling in outer rainbands suppresses convective activity in outer rainbands and is unfavorable for the SEF.3.When the area-averaged diabatic heating rate in outer rainbands and the eyewall become similar in magnitude, the secondary eyewall forms.

The precise implementation of the ecological water transfer project effectively promotes the enhancement of desert riparian ecosystem service value in the mainstream of Tarim River

Ecosystem service value (ESV), as a crucial indicator concerning human and regional ecological well-being, has always been a hot topic in academia. Selecting appropriate assessment factors for arid areas to comprehensively explore the spatial–temporal heterogeneity of ESV and proposing pathways for ESV enhancement are currently challenging in research. This study incorporates three driving indicators, namely, human disturbance intensity (HDI), vegetation growth status (NIRv), and hydrological wetness condition (TVDI), into ESV calculation, efficiently improving the pixel-scale spatial heterogeneity manifestation of ESV. The study was conducted in a representative desert region of the Tarim River Basin (TRB), where ecological water transfer has effectively facilitated vegetation restoration. Based on this analysis, the total ESV in the TRB grew by 12.73 % between 2000 and 2022. Among them, ESVHDI, ESVNIRv, and ESVTVDI increased by 4.10 %, 58.25 %, and 18.78 % respectively. ESV in the four source rivers and mainstream of TRB increased by 4.36 % (YR), 60.77 % (TR), 2.94 % (AR), 3.88 % (HR), and 2.11 % (KR), with the ESV enhancement areas highly coinciding (coincidence degree is as high as 60.64 % of the mainstream of TRB) with the Populus euphratica forest water transfer area. ESV in the ecological water transfer area increased by 51.27 %, especially in the mainstream of the TRB water transfer area, where ESV increased by 62.32 %. Based on the perspectives of water use benefit (ESV/ET) and efficiency (ET/NIRv), to improve the ecological water use efficiency and ESV even further, the water supply thresholds of forests, grasslands, and wetlands should be controlled within the ranges of [495.37 mm-553.45 mm], [474.25 mm-528 mm], and [1011.68 mm-1070.64 mm], respectively. This study not only provides new insights for ESV calculation in arid areas but also offers scientific guidance for precise management of arid ecosystem.

Modelling of the trade-off between the deep soil moisture and vegetation restoration in the hilly area of the Loess Plateau, China

Excessive depletion of soil moisture by artificial forests in the vegetation restoration areas of the Loess Plateau has attracted widespread attention. To assess potential risks of soil moisture deficit, we needed on-site vegetation and soil sampling data, as well as UAV images from the Chaigou Watershed for three-dimensional analysis, combining both sampling and raster data. Three-dimensional surfaces for assessment of trade-off were established innovatively by the local regression and interpolation methods. The results indicated that soil moisture benefits at 20–40 cm depth are lower than at 0–20 cm due to infiltration and surface disturbance. In some areas of the Chaigou Watershed, grass and shrub-grass vegetation are facing risks of soil moisture deficit based on trade-off values (RSMD) and multiparameter evaluations. Analysis of deep soil water content variability revealed the moisture decreases significantly with the deepening of the soil layer in some plots. R (Richness), H (Shannon’s Diversity), Margalef, COHESION, and CONTAG were applicable in interpolation and fitted with the local regression model (R2 > 0.6) corresponding to the trade-off, but SPLIT was proven to be inapplicable in this study area. The zero trade-off inflection points were 6 %–8 %, while the trend inflection points were 7.5 %–9 % for soil moisture and vegetation indices of vegetation and landscape in typical sampling sites of the Chaigou Watershed. Three-dimensional fitting model is more comprehensive and effective in assessing deep soil moisture conditions and grass plots on shady slopes generally had the best trade-off status in this region.

Improving ecosystem respiration estimates for CO2 flux partitioning by discriminating water and temperature controls on above- and below-ground sources

Empirical models for estimating ecosystem respiration (ER) are widely used in CO2 flux partitioning algorithms that partition net ecosystem CO2 exchange (NEE) into gross primary productivity (GPP) and ER due to advantages of simple structures. However, empirical ER models remain limited due to single-source conceptualization that doesn’t discriminate different responses of aboveground respiration (AGR) and belowground respiration (BGR) to environmental factors (i.e., temperature and/or soil moisture). In this study, a dual-source module with only one parameter α was proposed and incorporated into six widely used ER models to enhance model capabilities. Long-term flux measurements of six typical terrestrial ecosystems and soil chamber respiration data at two sites were collected to evaluate models. Results showed that integration of the dual-source module can significantly improve the performance of empirical models in selected ecosystems with mean R2 improvement of 0.10 ± 0.16. The site years with relative increased R2 (ΔR2) larger than 10 % range from 6 % to 79 % amongst different models. Further validation between soil respiration and estimated BGR showed good correlations (r > 0.7) and demonstrated that proposed method can provide robust estimate of above/belowground respiration. Calibrated α varies amongst ecosystem types. Further analysis indicates variation of α is largely influenced by ratio of above/belowground biomass and annual average moisture conditions. Our findings highlight the critical need for partitioning ER models into dual-source for developing CO2 flux partitioning algorithms and support the approach as an effective means to enhance the understanding of global carbon cycles with changing climate.

Insight into drilling performance parameters for in-situ detection of lithological transition

In order to examine the rock dependence on drilling performance parameters, such as torque and rate of penetration (ROP), we conducted laboratory drilling experiments using mafic and ultramafic rocks from the Oman ophiolite and the Horoman Complex. Serpentinized peridotite shows approximately twice the ROP (dry conditions: 2.95 ~ 3.85, wet conditions: 8.25 ~ 10.3 × 10−5 m/min) compared to that of peridotite and mafic samples (dry conditions: 4.75 ~ 6.90, wet conditions: 14.5 ~ 18.3 × 10−5 m/min) under both dry and wet conditions. This result is likely due to the reduction in fracture strength associated with serpentinization. We compared the laboratory results of drilling parameters with in situ data obtained from IODP Expedition 360 drilling of gabbro and Expedition 399 drilling of serpentinized peridotite, using the equivalent strength method to normalize ROP to the given rotation rate and torque. The calculation results show that the normalized ROP for the serpentinized peridotite formation was systematically higher than that for the gabbro layer, which is in agreement with our experimental results. We propose that the in situ drilling performance parameters can be used to detect the lithological transitions, such as serpentinite.

Analysis and optimization of dynamic response during the startup process of proton exchange membrane fuel cell

Proton Exchange Membrane Fuel Cell (PEMFC) is a prominent application of hydrogen energy in fields such as mobile devices, vehicles and small-scale energy systems. This study experimentally investigates transient response of the automotive PEMFC when starting with different load under various operating conditions, which significantly influences durability. The key finding is that dynamic behavior follows a “two-stage” response mode under drier conditions. The first stage is related to the diffusion processes of cathode gas and the second stage is determined by the membrane rehydration process. Under wetter conditions, dynamic behavior exhibits a “three-stage” response mode with a larger voltage fluctuation and longer startup time. The contributors to the first two stages are the same as the “two-stage” response mode and the third stage is determined by the degree of cathode flooding. Results indicate that increasing cathode stoichiometry, cathode humidity, and temperature obviously enables PEMFC to startup more stable and faster and with a higher load. Besides, a step loading strategy with a gradually reducing magnitude achieves an optimal balance between response time and voltage fluctuation at the target load, with a moderate startup time of 9.6 s and minimal voltage fluctuation of 0.009 V.

Friction Modifier Performance in Twin-Disk Tests Using Disks of the Same Microstructure and Hardness

Friction management in the wheel-rail interface has received great attention from railway engineering in recent years, mainly due to the possibility of reducing wheel and rail wear. The addition of greases, lubricants and friction modifiers on the track has increased in the main railroads of the world. However, studies demonstrating the effect of applying friction modifiers are mainly carried out by manufacturers. To evaluate the action of the friction modifier, laboratory tests are less expensive tools and can give an indication of the benefit of the application. Thus, in this work, dry and wet twin-disk tests were carried out using disks with the same microstructure and hardness, evaluating only the action of the friction modifier. It was noted that the retentivity of the friction modifier had increased with the distance covered in the test. These results would contribute to increase the distance between applicators on the railway track and promoting a lower volume of product per distance traveled. The addition of a friction modifier also reduced the traction coefficient throughout the test, which contributed to lower wear of the disk. The friction modifier induced rolling contact fatigue cracks with greater depth and length due to hydro pressurization action. However, the addition was still beneficial because the wet condition keeping the friction at smaller values, the crack propagation takes longer to occur.

Assessment of Ablation Rates with Artificial Urinary Stones Appropriate for Simulation Training.

Introduction: Artificial urinary calculi are an essential tool for research and training in endourology. The goal of the study was to evaluate different types of artificial stones and how they behave to laser treatment, to finally determine which is the optimal one for training purposes. Materials and Methods: The stones were produced with a mix of Bego Stone powder and water, at mixing rates of 15:03, 15:04, and 15:06. They were evaluated in an in vitro experimental setting using the Quanta Cyber 150 W high-power laser lithotripter. Dusting was set to 0.5 J × 20 Hz = 10 W and fragmentation was set to 0.8 J × 8 Hz = 6.4 W. Stone weights were assessed in dry and wet conditions. Results: The ablation rates in the dusting modality were similar for the three stone types tested. In the fragmentation mode, the mean ablation rate for 15:04 artificial stones was greater than those of 15:03 and 15:06 stones. Overall, the mean weight difference between the wet and dry stones was 0.03 g. Consequently, within the stone types tested, 15:04 artificial are probably the most convenient ones for training purposes because they get disintegrated similarly to 15:03 and 15:06 Bego Stones on a dusting setting, and ablation is faster on a fragmentation setting. Conclusions: The 15:04 Bego Stones may be considered as the optimal option for use in simulation training models of the endourological education programs.

ВЛИЯНИЕ ПРИМЕНЕНИЯ БИОПРЕПАРАТОВ НА ОСНОВЕ РАЗЛИЧНЫХ ЭНДОФИТНЫХ БАКТЕРИЙ РОДА BACILLUS НА ФИТОПАТОГЕННЫЕ МИКРОМИЦЕТЫ И ПРОДУКТИВНОСТЬ ЯРОВОЙ ПШЕНИЦЫ

The studies were conducted to assess the effect of using two biological biopreparations based on endophytic bacteria on phytopathogenic fungi and the productivity of spring wheat of the Ulyanovskaya 105 variety. The studies were carried out in years with both favorable (2020, 2022) and extremely dry (2021) moisture conditions during the growing season. Field experiments were laid on highly fertile gray forest soil in the Predkama zone of the Republic of Tatarstan. Bacillus monojavensis PS17 (endophytic seed bacterium) and Bacillus amyloliquefaciens RECB-95 (endophytic root and stem bacterium) bacteria were used as biological agents. Biopreparations based on these bacteria were used for seed treatment (rate of 1 l/t) and for spraying plants in the heading phase (1.0 l/ha). The control variant was without any treatments, and the standard was the scheme using chemical fungicides (seed treatment with Lamador (0.2 l/t), spraying with PropiShans (0.5 l/ha)). In laboratory conditions, high fungicidal activity of Bacillus mojavensis PS17 and Bacillus amyloliquefaciens RECB-95 against Fusarium fungi was found. An advantage of using Bacillus amyloligurosine RECB-95 when treating spring wheat seeds in suppressing Fusarium infection in the soil of the root zone of plants was found. Both strains, when treated with seeds, suppressed the development of Cochliobolus sativus in the soil of the root zone of wheat plants. The most effective control of root rot at the early stages of spring wheat plant development was ensured by using the scheme with seed treatment with Bacillus mojavensis PS17. The use of biopreparations based on endophytic bacteria reduced the development of leaf mycoses of spring wheat, and no significant differences were noted between strains in terms of disease control efficiency. The strongest positive effect on the yield of spring wheat was exerted by the use of biopreparations based on endophytic bacteria under conditions of an extremely dry vegetation period. The maximum yield of spring wheat was ensured by the biological protection scheme with the endophytic bacterium of wheat seeds Bacillus mojavensis PS17.

Mechanism of Irrigation Before Low-Temperature Exposure on Mitigating the Reduction in Yield Loss and Spikelet Abortion at the Jointing Stage of Wheat

The increasing frequency of low-temperature events in spring, driven by climate change, poses a serious threat to wheat production in Northern China. Understanding how low-temperature stress affects wheat yield and its components under varying moisture conditions, and exploring the role of irrigation before exposure to low temperatures, is crucial for food security and mitigating agricultural losses. In this study, four wheat cultivars—semi-spring (YZ4110, LK198) and semi-winter (ZM366, FDC21)—were tested across two years under different conditions of soil moisture (irrigation before low-temperature exposure (IBLT) and non-irrigation (NI)) and low temperatures (−2 °C, −4 °C, −6 °C, −8 °C, and −10 °C). The IBLT treatment effectively reduced leaf wilt, stem breakage, and spikelet desiccation. Low-temperature stress adversely impacted the yield per plant—including both original and regenerated yields—and yield components across all wheat varieties. Furthermore, a negative correlation was found between regenerated and original yields. Semi-spring varieties showed greater yield reduction than semi-winter varieties, with a more pronounced impact under NI compared to IBLT. This suggests that the compensatory regenerative yield is more significant in semi-spring varieties and under NI conditions. As low-temperature stress intensified, the primary determinant of yield loss shifted from grain number per spike (GNPS) to spike number per plant (SNPP) beyond a specific temperature threshold. Under NI, this threshold was −6 °C, while it was −8 °C under IBLT. Low-temperature stress led to variability in fruiting rate across different spike positions, with semi-spring varieties and NI conditions showing the most substantial reductions. Sensitivity to low temperatures varied across spikelet positions: Apical spikelets were the most sensitive, followed by basal, while central spikelets showed the largest reduction in grain number as stress levels increased, significantly contributing to reduced overall grain yield. Irrigation, variety, and low temperature had variable impacts on physiological indices in wheat. Structural equation modeling (SEM) analysis revealed that irrigation significantly enhanced wheat’s response to cold tolerance indicators—such as superoxide dismutase (SOD), proline (Pro), and peroxidase (POD)—while reducing malondialdehyde (MDA) levels. Irrigation also improved photosynthesis (Pn), chlorophyll fluorescence (Fv/Fm), and leaf water content (LWC), thereby mitigating the adverse effects of low-temperature stress and supporting grain development in the central spike positions. In summary, IBLT effectively mitigates yield losses due to low-temperature freeze injuries, with distinct yield component contributions under varying stress conditions. Furthermore, this study clarifies the spatial distribution of grain responses across different spike positions under low temperatures, providing insights into the physiological mechanisms by which irrigation mitigates grain loss. These findings provide a theoretical and scientific basis for effective agricultural practices to counter spring freeze damage and predict wheat yield under low-temperature stress.

Effect of the surrounding environment on electron beam irradiation damage of enhanced green fluorescent protein

Fluorescent proteins exhibit fluorescence and photoconversion, which are used to study biological phenomena. Among these, enhanced green fluorescent protein (EGFP) emits cathodoluminescence when irradiated with electron beams; this phenomenon has numerous applications in new research tools for biological phenomena. However, bleaching during electron irradiation is a major problem. Generally, the presence of water is important for biological samples, and structural observations are often performed under cryogenic conditions. One of the advantages of cryogenic conditions is the stabilization of the sample due to cooling. However, it is unclear which factor is more effective: the presence of water molecules or cryogenic preservation. To explore the stabilizing factors of the sample structure, we prepared four environments around the sample–dry at room temperature, wet at room temperature, dry at low temperature, and under cryogenic conditions–and investigated the electron beam irradiation damage by measuring the fluorescence emission spectra. Emission intensity from EGFP was attenuated, and the peak was red-shifted by electron beam irradiation; however, the intensity attenuation was fast under dry conditions at low temperature and slow under wet conditions at room temperature. These results imply that sample cooling has no significant effect on the stability of the EGFP chromophore and that the presence of water molecules is extremely important.